Olefin polymerization process



April 24, 1945- M. T. CARPENTER ErAL 2,374,272

OLEFIN POLYMERIZATION PROCESS Filed Aug. 2l, 1937 3 Sheets-Sheet l 1 nven fors Marr/L9 laarnfer Char/es AFeuchfer ATTORNEY April 24, 3945 M. T. CARPENTER ETAL 2,374,272

OLEFIN POLYMERI ZATION PROCESS Filed Aug. 2l), 1937 I 3 Sheets-Sheet 2 9j 110 9- 93a l r 101 y0 ya A I nveniors Marr/L9 Carpe/#ef- F 1291 2 Char/esEFea/chfer AMM ATTORN E Y M. T. CARPENTER ETAL 2,374,272

OLEFIN POLYMERIZATION PROCESS pri 24, 1945.

3 Sheets-Sheet 3 `Filed Aug. 21, 1957 P 4 .5@ mmm M .www/U y www F mfr, I1 rN o0 0 A .u l W 6 i ATTORNEY Patented Apr. 24, 1945 Morris T. Carpenter, Chicago, lll., and Charles F.

Feuchter, Hammond, Ind., assig'nors to' Standard Oil Company,'Chicago, Ill., a corporation of' diana Application August 21, 1937, Serial No. 160,264

Claims.

This invention relates to a process of manufacturing hydrocarbin 'resins and, in particular,

resins produced -by the polymerization of unsaturated hydrocarbons with the said of catalysts. 'I'he unsaturated hydrocarbons with which we are most concerned are the low molecular weight olens, and especially the gaseous olens such 'as butylene and isobutylene. The catalysts employed are the halides'of amphoteric metals and those metal halides in general which are hydrolyzed by water to form halogen acids. Aluminum chloride Vand boron uoride are most suitable, although titanium chloride, stannic chloride, etc. may be used.

One object of the invention is to provide a process for carrying out the polymerization of olens at ordinary and'extremely low temper-v atures, for example as low as 200 F. Another object of the invention is to recover and reemploy the catalyst. Still another object of the invention is to facilitate the handling .of the resinous product. Yet another object of the invention is to utilize eicient heat exchange to economize on refrigeration without deleterious effect on the product. Other objects and advantages will be apparent from the following description.

Figure 1 isa diagrammatic drawing showing the process in general layout. Figui'e 2 is a more detailed drawing of the reaction chamber I8 in Figure 1. Figure 3 is a modied form ofthe reaction chamber I8 which may be employed. Figure 4 illustrates a method of refrigerating which may be used in the process. Figure 5 shows a modified form of refrigerating apparatus and method.

I8. Iifpassing through heat exchangers Il and I6 the temperature of the hydrocarbons is successively lowered to the desired reaction temperature which will usually lie between 0 and 100 F. and may'go as low as 200 F. A'reaction temperature of 80 F. is suitable for the polymerization of isobutylene and somewhat higher' temperatures may be used for the polymex-ization of other olens.

In the reaction chamber I8 there is provided means for absorbing the heat of reaction produced by the polymerization ofthe olens, ap-

paratus for thispurpose being shown in greater detail in Figure 2. Referring to Figure 1, into the stream of cold liquid olen hydrocarbon in reaction chamber I8 there is introduced a suitable catalyst which may be boron fluoride. Boron fluoride may be produced in generator I8 by the interaction of ammonium uoborate, boric' acid and sulfuric acid, whence it is led byline 20 to reaction chamber I8. If desired, it may be compressed and stored in storage cylinder 2| from by line 23 at a point near the opposite end of Referring to Figure 1, liquid olens, which may Y be pure oleflns or a mixture such as the butane fraction'from a gas absorption plant, consisting largely of butylenes and butanes from cracking still gases. preferably freed from HzS and other forms of sulfur, are withdrawn from supply tank I 0 by valved line II leading to drier I2 where moisture contained inthe hydrocarbon may be' removed by a suitable dehydrating agent such as calcium oxide, calcium chloride, silica gel, etc.`

We prefer to employ a liquid butane fraction which is substantially free from higher boiling the reaction chamber from the hydrocarbon inlet in order to obtain countercurrent treatmentdescribed more fully in connection with Figure 2.,

The amount of BF: added is suiiicient to produce a catalyst concentration of .05 to 0.1% of the` hydrocarbon treated, although larger amounts, e. g. 0.2 tu 1% may beAemployed to obtain rapid reaction, the unreacted portion being recycled as hereinafter described.

The reaction chamber I8 may be constructed in different ways, but it is essential that it provide a large surface for heat exchange between throttling valve 25a, and the refrigerant vapor may be Withdrawn from the reaction chamber, conducted by line 26 to compressor 21 and .oo ndenser 28. and returned vto storage tank 2l. Re-

frigerant vapors in line 26 may be heat exchanged withfeed'to reactor I8 if desired. Re-

frigerant may be drawn from the same Storage tank 24 'by lines 25 and 29 to provide cooling in exchanger I6. 'I'he expansion of the refrigerant through valve 30 produces the desired degree of cooling for 'the liquid hydrocarbons prior to intemperatures employed.

troducing the catalyst, and the refrigerant vapors are conductedby line 3I to compressor 2'I previously described. l

Liquid ethane or ethylene or ethylene-propane mixtures may suitablyl'be employed as refrigerants and have advantages over carbon dioxide in their freedom from solidification at low temperatures. temperatures as low as 70 F. or lower, it is advisable to employ acetone, ether or other suitable organic liquid in reactor I8 to prevent the carbon dioxide from solidifying. The reaction chamber I8 is constructed to provide sufficient reaction time at the low temperature to bring about the desired polymerization of isobutylene. In the case of polymerization oi' isobutylene with an excess of-boron fluoride at '-80 F. a reaction time of approximately 5 minutes should be provided, the lvolume of the reaction chamber I8 and the rate of flow of oleiins action chamber I8 the polymer-ized hydrocarbon mixture is led by line 32 to pump 33 where it is jforced through line 34 to heat exchanger I4 where itserves to preliminarily refrigerate the olefinsin line I3. If desired, suflicient pressure may be employed in the reactor I8 to make the use of pump 33 unnecessary, in which case bypass 33a may be used. Because of the low temperature of the sin'eam in line 32 difficulty has been found in lubricating pump 33 and this problem has been successfully solved by employing as the lubricant a solution of the reaction product in liquid butane. A concentration of about 20 to 30% of the resin in liquid butane is satisfactory and the solution will not congeal at the low leaving heat exchanger I4 by valved line 35, the mixture of polymerized hydrocarbons is introduced into drum is where it is subjected to gentle heating by' means of coil' $1. Sumcient heating is supplied to evaporate from the mixture, part of the light hydrocarbons and substantially all the uncom- Where carbon dioxide is usedat `being taken into consideration. From the rebined portion of the boron fluoride catalyst, the

vapors of which are conducted by line 38 to cooler 38 and compressor 40, thence by line 22 to reaction chamber I8. In this way the uncombined portion of the catalyst is conveniently recirculated and used repeatedly. Instead of being .directly admitted into reaction chamber lsl by' line 22 the recovered catalystmay be introduced into the fresh catalyst supply line 23 by opening valve 4I and closing valve 42.

Fromthebaseofdrum amixture of polymei-ined hydrocarbons is withdrawn by une u to stripper 44 wherein substantially all the light hydrocarbons are removed from the polymerized product. In order to facilitate handling the viscous product of polymerization a suitable diluent may b e introduced by line 45 from supply tank 48. Hexane, benzene or other solvent, for

y example hydrocarbon lubricating o il, may be employed for this purpose. A The amoimt of diluent thus added may conveniently be from one to four times the volume .of the resinous product contained in the hydrocarbon mixture leaving drum as. A pafticuia-ly mutable diluent is alight lubricating oil of S. A. E. 10, 20 or 30 grade or' v quenching liquid such as alcohol, moist acetone,

liquid ammonia, alcoholic sodium hydroxide,V etc.,

which reacts with and deactivates any residual catalyst not removed in drum 36 or previously. As a result, further action of catalyst on the product and on other hydrocarbons is substanstantially prevented at the moreQelevated temperatures in stripping tower 44. We may also wash the polymer product in the butane solution at this point in the process by contacting with aqueous sodium hydroxide or other alkali, preferably followed by water, means for accomplishing this not beil'rig illustrated in the drawings. formation of colorin the product is thus prevented by complete neutralization.

Stripping tower 44 is preferably operated without the use of live steam, heat being supplied by closed coil 48. Butane is driven oi through vapor line 49 and may be discarded from the system as fuel gas or partially condensed and recycled as a diluent for theolen hydrocarbon entering the process, if desired. The polymerization product containingg some residual butane in solution, for example l to 20%, is withdrawn from the base of stripper 44 and conducted by line 50 and pump 5I to heating coil 82 where it is heated to an elevated temperature, for example 200 to 350 F., and discharged into flash drum 53. neutralized previous to stripper 44, it is preferred to subject it to further washing with sodium hydroxide or other alkali and water after leaving stripper 44 and before introducing into heater 52 in order to prevent decomposition and formation of color'l Drum 53 may suitably be maintained under vacuum by exhauster 54 and the butane-free product may be withdrawn byline 55.

In the case where the product has been diluted with a heavy hydrocarbon oil introduced from tank 46 the diluent will be retained in the solution and the diluted rproduct thus obtained may be employed directly for the treatment of lubricating oils, etc. Where lighter diluents, such as hexane, light naphtha, etc., are employed as dluents'these will be removed in ash drum 53 along with residual butane.

Where it is unnecessary to completely remove the light diluent from the product, it may be withdrawn from the base of stripper 44 by opening the valve in line 50 and discharging through wash tank 56 where an alkali wash may be employed to remove the final traces of acid or catalyst in the case where the stock has not been completely neutralized before enteringl stripper 44. The product is thereafter discharged through line 5l. 'Ihis .alternative method of treating the product may be employed when it isvused in the preparation of coating compositions, etc., where it is employed'in solution in volatile solvents.-

Instead of recovering catalyst by distillation from drum'38 in the mamner described, we may alternatively employ an adsorbent for this purpose. Thus. by closing valve 58 in line 34 and opening valves 58 and 60 in the lines leading .to

chamber 6I .we may divert the cold reaction stream through a bed of suitable adsorbent retained in chamber 8|. Granulated vfullers earth may be used for this purpose, aluminum silicate. silica gel etc.- The absorbent employed ifn this manner removes the uncombined catalyst togather with any catalyst sludge or complex compounds contained in the reaction products. .If desired, excess catalyst mayv be recovered from the fullers earth by isolating the chamber 8l from the system and raising the temperature, the catalyst being swept from the absorbent by If the product has not been completely I or to any point in the reaction tower by extend,

hydrocarbon vapor stream and conducted back into the polymerization system.

. I'n a similar manner we may also divertthe stream passing 'through line 43 into decolorizingY chamber sz suitably charged 'with funers earth or other decolorising adsorbent, valves 63, 64 and 65 being provided for this purpose. When so operating we may introduce a light diluent naphtha, lubricating oil or other diluent through valved line 45a if desired. When employing ad sorbent tower 62 we nd it unnecessary to intro# duce a quenching agent through line 41 as previ-l ously described, since the adsorbent may be employed to remove any traces of catalyst which, if left in the reaction product, would promote undesirable polymerization or depolymerization and deterioration, when heated to a higher temperature in stripper 44 for example. Instead of removing the catalyst from the stock in line 34 by means of the adsorbent chamber 6| .we may alternatively accomplish this by vacuum distillation, stripper 66 being provided for this purpose. Vacuum pump 61 serves to maintain a low pressure of the order of to 50 mm. mercury and the hydrocarbon reaction product charged to the stripper by; line 68 is substantially denuded of volatile BFa catalyst, some low boiling hydrocarbons being simultaneously withdrawn. If desired, this hydrocarbon vapor containing active catalyst may be recycled to the reaction chamber by way of line 38. Heat and/or inert stripping gas may be introduced to the base of stripper 66 by line 69 if desired. A suitable valve 10 is provided to divert the stream of hydrocarbon reaction products into the vacuum stripper. When employing stripper 66 to remove excess catalyst we may immediately thereafter introduce into the reaction stream a catalyst quenching liquid such as alcohol, liquid ammonia, etc. hereinbefore described.

When employing clay tower 6| or vacuum stripper 66 to remove excess catalyst it will not be necessary to subsequently remove catalyst from the reaction products subsequent to heat exchange in exchanger I4. In that case stripper 36 may be by-passed by conducting the stockV through valved line a.

Referring to Figure 2 for a more detailed description of the reaction chamber, casing 80sur rounds refrigerator coil 8| which is supplied with refrigerating liquid through pipe 82. The coil 8| is suitably comprised of three or more concentric nested spirals connected on the inlet endl t0 header 83 and at the outlet end to header |34 leading to refrigerant discharge pipe 8 5. In order to reduce the free space in the reactor and confine the stream.of reacting liquid to -close contact with the 'refrigerator coil 8|, aller or liner 86.

suitably made of aluminum, which is anv alloy steel containing about 16% chromium and 8% nickel, monel, 'or other material not attacked by reactants, may-be employed. Similarly, re-

frigerated core 86a may occupy the space within the spiral coil 8|.

Olen hydrocarbon liquid which has been pre- 'cooled is introduced into the reaction chamber through feed inlet 81 which, if desired, may be connected by pipe 88 to distributor ring 89. A similar arrangement may be employed at the bottom for introducing the catalyst which may be a solution or a gas, for example -BF3. Catalyst inlet 90 may be connected by pipe 9|- to catalyst distributor sz. If desired the point of introduction of the catalyst may be shifted to the center ing or shortening pipe 9|.

Removable heads 93 and 84 bolted to flange 00a and 94a, which in turn are welded to casing 00', are provided with the proper passages for introducingr and withdrawing materials from the reaction chamber, making pyrometer connections, etc. For convenience in assembling they are provided with packing glands and nuts 95 and 96.

When operated in the vapor lled manner the reaction chamber permits the hydrocarbon to cascade over the cooling coil ll in counterilow to vapors .of the BFa catalyst, thus absorbing BF: gradually and permitting complete utilization of catalyst and giving the desired control of the reaction. The reaction chamber may also be operated with the cooling coil 8| submerged, in which case the BFs catalyst gas may enter the liquid and be absorbed before escaping from the vent 91. Because of more rapid absorption of catalyst in the latter case it is desirable to intraduce the catalyst at an intermediate point in the reaction chamber between the refrigeratlng coil headers 83 and 84 in order to provide time and space for the reaction to take place before the hydrocarbons escape from the chamber.. The polymeri'zed product is withdrawn from the reaction chamber through outlet 98.

Referring 'to Figure3 which describes a modied form of reaction chamber, casing or tower |00 is provided for refrigerant inlet |0| and outlet |02. Any suitable refrigerant may be employed, for example cold brine, cold oil, liquid ammonia, liquid propane and, for very low temperatures, liquid ethane or liquid methane may be used in suillcient quantity to substantially nll the tower |00. Hydrostatic pressure on the refrigerant may be avoided by applying it as a froth or spray. By using liquid ethane a temperature of J F. may conveniently be obtained and if lower temperatures are desired the pressure in the tower may be reduced by vacuum pump |03. If liquid ammonia or propane are used temperatures of about 40 F. may be obtained which may be still further reduced to 60 F. or below by use of vacuum. 'Ihe vapors withdrawn through refrigerant outlet |02 may be conducted by by-pass line |04 to compressor |05 and condenser |06 leading to refrigerant receiver |01 whence refrigerant is allowed to expand again in reaction chamber |00.' In the case where brine or other liquid unvaporized refrigerant is used additional refrigerating means are required to externally cool it to the desired temperature.

Within the chamber |00 is located reaction coil |08 with inlet |09.and outlet ||0. 'I'he coil |00l inl a confined stream surrounded by indirect refrigeration may be employed. A multiple coil of small diameter tubing may be employed to insure rapid heat transfer between the reacting mixture and the surrounding refrigerant. The liquid isobutylene mixture is forced throughthe coil at a rapid rate and it is desired that it be precooled by external heat exchange to the desired reaction.

temperature before entering reaction chamber |00. If it is properly precooled, the catalyst, for

example BF; or AlClz solution' or suspension, may

' reaction the catalyst may be distributed through be introduced at the inlet of the coil-through pipe but to obtain more uniform control lof the out the length of the coil |00 by introducing it at one or more intermediate points simultaneously if desired, viz.: ||2, H3, etc.

^ In order to more conveniently obtain the low temperature necessary for conducting the polymer-ization of isobutylene we may employ the apparatus described in Figure 4 in which the reaction chamber with coil connections |2| and |22, refrigerant inlet |23 and outlet |24, is shown connected to suitable apparatus for supplying a low boiling refrigerant liquid such as liquid ethane. Liquid isobutylene alone or in solution in a suitable diluent is preliminarily cooled by heat exchangers not shown but similar to exchangers I4 and I6 in Fig. l where the isobutylene stream is countercurrently chilled by the. refrigerant. It is then introduced into the reaction coil in chamber |20 where it is cooled concurrently with the refrigerant introduced by line |23. The catalyst is preferably introduced into line |22 at the inlet of the reaction chamber after 20 the temperature of the butylene stream has been reduced to the desired reaction temperature. The concurrent cooling in reaction chamber |20 serves to supply maximum' cooling immediately following the introduction of catalyst, thus removing 25 to liquefy it in the summertime when.coo1ing 30 water temperatures are relatively high. This problem is still more aggravated when using methane. At these times we may conduct the ethane gas through line |24 to compressor |25 where it is compressed and passed through cooler |26 suitably supplied with cooling water..A From the cooler the gas passes to trap |21. where any liqueed portion of the gas, particularly any heavier impurities, which may be at a temperature of between 80 to 90 F., is collected and re- 40 moved by line |28 and liquid transfer'pump |29 which returns the liquid ethane to the reaction cizlzigmber |20 by line |30 and cooler 3| and line tion of ethane because of its rather low critical condensation temperature and also to obtain greater flexibility in choice of evaporation temperature. we may resort to the practice of introducing into the ,ethane or ethylene a relatively Vsmall amount of higher boiling hydrocarbon such as propane, butane or hexane, the effect of which addition is to raise the critical condensation temperature above that of pure ethane or ethylene gas. 'I'he evaporation temperature is also raised somewhat by the addition of the heavier hydrocarbon, but the amount of heavier hydrocarbon required will usually be relatively small and if the refrigerant is employed in a countercurrent manner the minimum temperature obtainable will not be greatly affected. By using the proper proportions of ethylene and propane, for example, we may thus approximate the physical properties of ethane with'respect to evaporation temperature and critical condensation temperature as we may also do by properly mixing ethylene with butane, pentane or hexane. Apparatus for refrigerating inthis manner is shown in Figure 5. Reaction chamber |40 equipped with hydrocarbon liquid coil |4| with inlet |4|a and outlet l4lb, refrigerant inlet |43 and outlet |44., is connected to a suitable refrigerant supply. Chamber |40 is equipped with suitable baflles |42 to insure contact between liquid cascading therein and the coil |4|. Vapors in chamber |40, consisting lin a large part of the lower component of the ixed refrigerant, are withdrawn by4 vapor line V|44 leading to compressor |45 and condenser |46. An increasing proportion of the higher boiling component or components and a decreasing proportion of the lower boiling component cascade to the lower part'of the chamber |40 in the liquid phase forming a liquid layer with surface below the vapor outlet line |44. Compressor |45 may suitably increase the pressure to about 400 to 700 pounds per square inch which is maintained in condenser |46. Condenser |46 may contain suitable baffles |41 and cooling coil |48 supplied with cool- Any uncondensed ethane is withdrawn from 45 mg Water,

trap |21 and conducted by line |32 and condenserx) |33 which is supplied with a refrigerant from an auxiliary refrigerating system. A suitable refrigerant for this purpose is liquid ammonia, liquid propane, liquid butane, liquid SO2, dichlor' difluor methane, etc. By this means the temperature in |33 is reduced substantially below the critical temperature of'ethane and no difliculty is encountered in liquefying the remainder of the gas which may notliquefy in cooler |26.`

are withdrawn by line |31 leading to compressor |33 which,vin turn, discharges the vapors into condenser coil4 |39 whence the refrigerant ows back to theauxiliary -refrigerant supply tank.

|35. Auxiliary refrigerant may likewise be used to cool the liquid 'ethane in cooler |3| for example to a temperature of -50 F., thus conserv- -ing refrigeration necessary to maintain4 the low-V temperatures of the reaction chambev- |20. Alternatively, if desired, cooler 3| may be a heat exchanger supplied with cold gas from line |24.

In order to avoid diiiiculty with the condensa- 75 Liquid propane, butane, hexane, etc. may be introduced into the condenser through line |49 in small amounts as needed to raise the critical temperature of the ethane gas suflicient for condensation by contact with the cooling coil |48. The condensed ethane, carrying some higher boiling hydrocarbon in solution, is then conducted by line |50 tocooler |5| and line |52 back to chamber |40, the pressure being reduced on 'enteringchamber |40 by expansion valve |53. Additional ethane or the higher boiling hydrocarbon may be introduced into the system from time to time as needed by inlet |54. y Y

Unevaporated liquid collected in the base of tower |40 is withdrawn by line |55 and pump |56- and returned through line |51 to the upper part of the condenser |46 wherein it is distributed through inlet |49. In this way any higher boiling hydrocarbon. which does not evaporate in the tower |40 is prevented from accumulating therein and is brought back tothe absorber where' its eifect in raising the critical temperature` of the ethane therein is maintained.

In still another modification of our invention ,-w'e may `conduct the fpolymerization reaction in direct contact'withfthe refrigerant employed to maintain the desired low temperature. Thus we may add liquidpropaneor ethane to the olefin hydrocarbon, lprecool the mixture and introduce it into the reaction chamber where it is brought into contact with the catalyst. In lthis casethe reaction chamber may be providedwith no reirlgerating means but merely with suitable heat insulation to conserve refrigeration.

When using this method the temperature of the reaction may be controlled by regulating the pressure towhich the reaction chamber is subjected. Thus, by employing liquid ethane as the refrigerant in direct contact with the reaction mixture'at atmospheric pressure a temperatureof about 120 F. may b e obtainedi employing liquid propane at atmospheric pressure, a temperature of about 40 F. may be obtained.

' If desired, the liquid refrigerant may be introduced at. the lower end of the reaction chamber `and the olen hydrocarbon at a higher Ipoint and the extent of refrigeration may be obtained by regulating the rate of introducing refrigerant as well as the pressure. When employing direct contact refrigeration in this manner the vapors oi the refrigerant escaping from the reaction chamber may carry away a portion of the catalyst in vapor form, especially in the case of boron trluoride which has a. high vapor pressure. By liquefylng and recirculating the refrigerant vapors containing catalyst, any catalyst removed in this way may be returned to the system without incurring loss of valuable catalytic material.

Although several catalysts may be employed for canying out the present process the boron uoride catalyst is advantageous because of the fact that it is gas even at very low temperatures and can be readily manipulated and recovered by evaporation from the reaction products. In the case of other catalysts which are not gaseous, such as aluminum chloride, it islconvenient and sometimes necessary to use them in the form of solutions in' solvents which may be other fluid metal halides, organic so1vents,`such as nitrobenzene, etc. If desired,.the boron fluoride may be supplemented by other catalysts and also promoted by halogen acids, particularly hydrogen fluoride and hydrogen chloride. Where aluminum chloride is used continuously it may conveniently be added in the form of a slurry or suspension for which purpose a portion of the unreacted hydrocarbon material obtained from the process may be recirculated.

In a typical operation of our process we may employ a mixture of butanes' and butylenes containing about 20% of isobutylene which it is desired to polymerize. The hydrocarbons may -be cooled to a temperature of 100 F. and charged to the reactor at the rate of 10 gals. per min. A t the point of entering the reactor boron iluoride may be introduced at the rate of 4 to 5 pounds per hour which is equivalent to about 0.15%. We have found that from about .02 to .08% by weight of boron iluoride, depending on the amount of poisons present such as sulfur compounds, is used up in the process, thus leaving from .05 to .13% to be recovered and recirculated in this operation. Where a more rapid reaction rate is desired higher concentrations of catalyst may be employed and the excess may be recovered and recirculated substantially without loss.

Cooling is provided in the reactor at a suilicient rate t0-maintain the temperature below 70 F.

Unused boron fluoride is recovered from the reaction product in an amount oi about 2-4 pounds Der hour which is recycled to the reactor. The unchanged butanes and butylenes are removed and substituted by hexane to give a ilnal product obtained is 100 pounds per 100 gals. of butanebutylene mixture charged to the apparatus.-

In order to obtain the dry" resin tree from solvent it may be evaporated, care being taken to' avoid loss by roaming. A suitable nlm type evaporator may be used xor this purpose. Alternatively, the resin may be retained in butane solution as produced in the process, a small pressure being required and no diluent being employed as shownv in Figure 1 by line la. The butane solution ol resin may be heated under pressure, preferably after neutralizing and washing to remove all traces oi' catalyst, as a result of which heating a major portion of the resin is precipitated from the solution. Any temperature in the vicinity oi' the critical temperature of butane may be used for this purpose and, in lact,\a temperature oi'v 15u to 250 r'. is suiiiciently high to precipitate most or the desired heavy isobutylene POlymers. Lighter polymers of. molecular weight substantially -below 1000 remain in solution inthe liquid butane and may be subsequently recovered for use as lubricating oils and in lubricating oil blending.

Another method of recovering catalyst which is somewhat more involved than those described hereinbei'ore consists in treating the cold reaction products from reaction chamber'l with anhydrous ammonia in sunlcient quantity to react with all boron liuoride present, forming an ammonium complex with Bre which is removed from the system and regenerated by heating or treating with an acid. e. g., HzSOi. The complex ammonium compound `may be removed from the system byvadsorption on fullers earth or similar means.

l The resin produced by our process -and appa.

ratus is a substantially colorless, odorless, nonvolatile plastic substance characterized by a very high molecular weight, usually within the range of 1,000 to 12,000, but molecular weights of 20,000 to 30,000 may be obtained. its density ls-Slightly less than that of water and its refractive index is about 1.503 to 1.507. The resin retains its plastic nature over wide ranges of temperature, down to 100 F. and lower, although atthe temperature of liquid air it becomes a brittle solid. At elevated temperatures it becomes soit and semi-fluid `but never completely loses its viscidity.4

Although we have described our process particularly as applied to the manufacture of a viscous plasticr resin, certain features of the process seconds Saybolt at'2l0" F. and a visccsityindexVV of 110 to 13,0. In addition to the high viscosity index it -is` characterizedby a low pour point and extremely low carbon residue, about 0.1%. These oils have been found especially suitable for use in shock absorbers and other apparatus requiring oils of low susceptibility to temperature change and low pour point. c

approximately 20% or hydrocarbon We have described the polymerization of a commercial butane fraction containing isclutylene but we may also employ solutions of pure isobutylene with suitable diluents. We prefer not to employ undiluted isobutylene because of the difculty of handling the viscous product in the polymerizer and lines. Examples of diluents which may be employed are hexane, propane, naphtha. etc.

A comercial b utane fraction obtained from the cracking of gas oil and other petroleum oils will usually contain about of isobutylene, al-

though concentrations from about 10 to 25% may conveniently be employed in our process. 'I'he remainder of the commercial butane fraction will usually be normal butane, normal butylene and isobutane with small amounts of propane and propylene. As previously mentioned, we prefer to fractionate-out from the raw material the fraction boiling in the range of pentenes when it is desired to obtain a high molecular weight resin. The amount of this fraction should preferably be reduced to 10% or less based on isobutylene present to avoid the undesirable effect ofreducing the molecular weight of the product.

Although we have described our process with respect to certain specinc examples, we intend that it be limited only by the following claims.

We claim:

1. In the process of polymerizing isobutylen in the liquid state with a boron iiouride catalyst at low temperatures, the steps comprising precooling a stream of liquid isobutylene and diluent hydrocarbons including butane tothe desired reaction temperature, introducing the required amount of boron ouride catalyst into said precooled hydrocarbon streamand immediately thereafter rapidly cooling and agitating the mixture of boron ouride catalyst and liquid hydrocarbons within a polymerization zone, withdrawing the reaction products from said polymerization zone, subjecting the reaction products and catalyst to' vacuum stripping v while maintaining the mixture below the boiling point of butane, re-

covering boron fluoride catalyst overhead from said vacuum stripping zone and recycling the stream of the liquid hydrocarbons is precooled to the desired reaction temperature, catalyst is introduced into said precooled hydrocarbon stream and immediately thereafter the mixture of Vcatalyst and liquid hydrocarbons is rapidly cooled and agitated within a polymerization zone, the improvement which comprises the steps of subjecting the reaction products containing catalyst to vacuum stripping, recovering vaporous catalyst overhead and recycling the recovered catalyst to the polymerization zone, withdrawing the polymer and unreacted hydrocarbons from the vacuum stripping zone, heating the unreacted hydrocarbons and the polymerization product substantially above the boiling point of the unreacted hydrocarbons, discharging the heated polymerization product and unreacted hydrocarbons into a receiver and separatingthe volatilized unreacted hydrocarbons from the polymerization product.

3. In the process of polymerizing olefin hydrocarbons in the liquid state with a vaporous metal halide catalyst at low temperatures wherein a stream of the liquid hydrocarbons is precooled to the desired reaction temperature, catalyst is introduced into said precooled hydrocarbon stream and immediately thereafter the mixture of catalyst and liquid hydrocarbons is rapidly cooled and agitated within a polymerization zone, the improvement which comprises the step of subjecting the reaction products and catalyst to vaccatalyst to the polymerization zone, withdrawing the substantially catalyst-free isobutylene polymer and diluent mixture from the vacuum stripping zone, heating the said polymerization product and diluent substantially above the boiling point of the diluent by indirectly contacting with imI uum stripping, recovering vaporous catalyst overhead and recycling the catalyst to the polyvacuum stripping zone, heating the said residual reaction product by indirectly contacting with the hydrocarbon stream flowing to the polymerization zone, introducing the heated and substantially catalyst-free polymerization product into a flash drum and separating the unreacted hydrocarbons and the polymerization product.

4. In the preparation of a hydrocarbon polymer the steps of polymerizng an oleiln in a solvent, heating the polymer solution to a temperature substantially above the boiling point of the solvent, discharging the heated polymer solution into a receiver and separating the volatilized solvent from the non-volatile polymer.

5. The process of claim 4 including the steps of effecting the polymerization in the presence of a amphoteric metal halide catalyst and removing said catalyst -from the polymer solution before recovery of the polymer.

MORRIS T. CARPENTER. CHARLES F. FEUCH'I'ER. 

